Police are appealing for witnesses of a "serious assault" in Kawerau on Friday afternoon.
Detective Senior Sergeant Paul Wilson said one person was found in a critical condition and was taken to hospital.
"Four young people were taken into custody and are assisting with our enquiries," he said.
"Police understand there were several other parties present at the time of the assault."
Police were called to the "altercation" at the intersection of Plunket St and Islington St just after 12:30pm.
Det Snr Sgt Wilson asked people who haven't yet spoken to police to come forward.
Anyone with information can call 105 and quote file number 240621/4014, or head into the Kawerau Police Station.
